Seiko LTPA245 Series Reference Manual
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Seiko LTPA245 Series Reference Manual

Seiko LTPA245 Series Reference Manual

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LTPA245 SERIES
LINE THERMAL PRINTER MECHANISM
TECHNICAL REFERENCE
U00060425801

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  • Page 1 LTPA245 SERIES LINE THERMAL PRINTER MECHANISM TECHNICAL REFERENCE U00060425801...
  • Page 2 Copyright © 2001, 2003 by Seiko Instruments Inc. All rights reserved. Seiko Instruments Inc. (SII) has prepared this manual for use by SII personnel, licensees, and customers. The information contained herein is the property of SII and shall not be reproduced in whole or in part without the prior written approval of SII.
  • Page 3 ! LTPA245B ! LTPA245C ! LTPA245D This technical reference, unless otherwise specified, provides information common to the LTPA245 series printers. Where the information differs depending on the printer model, the name of the relevant model is specified. Chapter 1 “Precautions” describes safety, design and operational precautions. Read it thoroughly before designing in order to ensure proper use of the printer.

  • Page 4: Safety Precautions

    CHAPTER PRECAUTIONS Read through this manual to design and operate the printer properly. Pay special attention to the precautions noted in each section. SAFETY PRECAUTIONS Follow these precautions when designing a product using the printer, and include any necessary precautions and warning labels to ensure the safe operation of your product by users. Preventing the thermal head from overheating When electricity is continuously supplied to the thermal head heat element by a CPU or other malfunction, the thermal head may overheat, causing smoke and fire.
  • Page 5 This technical reference, unless otherwise specified, provides information common to the LTPA245 series printers. Where the information differs depending on the printer model, the name of the relevant model is specified. If too much energy is applied to the thermal head, it may overheat and become damaged.
  • Page 6 Always monitor the output of the paper detector. Incorrect activation of the thermal head may damage and reduce the longevity of the thermal head and the platen. Since a reflection type photo interrupter is used in the paper detector, the detector may be affected by light from outside.
  • Page 7 When using the LTPA245B and LTPA245C: The printer does not have a platen block support function. Prepare the paper holder cover and fix the platen block to the cover. For the dimensions for mounting the platen block, see Figure 6-6. Platen block Prepare the paper holder cover and mount the platen block to the paper...
  • Page 8 When using the LTPA245D: The printer does not have a platen block support function. Prepare the paper holder cover and fix the platen block to the cover. For the dimensions for mounting the platen block, see Figure 6-6. When removing the platen block, follow the instructions shown in Figure 7-4 and continue to press the lock arm lever until the A portion of the lock arm (see Figure 7-4) comes up against the head block.
  • Page 9 1.2.2 Handling Precautions To maintain the initial level of performance of the printer and to prevent future problems from occurring, observe the following precautions. Also, include any necessary precautions to ensure the safe operation of your product by users. To protect the heat elements, ICs, etc. from static electricity, discharge all static electricity before handling the printer.
  • Page 10 1.2.3 Precautions on Discarding When discarding used printers, discard them according to disposal regulations and rules of each respective district.
  • Page 11 CHAPTER FEATURES The LTPA245 Line Thermal Printer Mechanism is a compact, high-speed thermal line dot printing mechanism. It can be used with a measuring instrument and analyzer, a POS, a communication device, or a data terminal device. Since the printer can be battery driven, it can easily be mounted onto a portable device such as a hand-held terminal.
  • Page 12 Low noise Thermal line dot printing is used to guarantee low-noise printing. Realizing easy design of outer case The printer mechanism is designed to fit easily into the outer case, allowing for reduced number of outer case parts. The external dimensions exclude those of the lever of the lock arm and the platen block. 41 g in mass includes all parts.

  • Page 13: General Specifications

    CHAPTER SPECIFICATIONS GENERAL SPECIFICATIONS Table 3-1 General Specifications Item Specification Print method Thermal dot line printing Dots per line 384 dots 8 dots/mm × 16 dots/mm (W × H) Resolution Print width 48 mm Maximum printing speed 427 dot lines/s (53.4 mm/s) (at 5 V) 616 dot lines/s (77 mm/s) (at 7.2 V) 720 dot lines/s (90 mm/s) (at 8.5 V) Paper feed pitch...
  • Page 14 Table 3-1 General Specifications (Continued) Item Specification Operating temperature range 0°C to 50°C No condensation Storage temperature range -25°C to 70°C No condensation Longevity (at 25°C and rated energy) Activation pulse resistance 100 million pulses or more (print ratio=12.5%) Abrasion resistance 50 km or more Paper width Paper feeding force...
  • Page 15 HEAT ELEMENT DIMENSIONS The printer contains a thermal head with 384 heat elements (dot-size). 48 mm (384 DOTS) 0.125 mm 0.0625 mm 0.125 mm Figure 3-1 Heat Element Dimensions mm (PAPER WIDTH) 5 mm 5 mm 48 mm (PRINTING WIDTH) 0.062 mm (PAPER FEED...
  • Page 16 PAPER FEED CHARACTERISTICS ! Paper is fed in a forward direction when the motor shaft is rotating in the normal direction (anticlockwise) when seen from the motor gear side. ! The motor is driven by a 2-2 phase excitation, constant current chopper method and feeds paper 0.0625 mm (equivalent to 0.5 dot pitch) every one step of the motor drive signal.
  • Page 17 STEP MOTOR CHARACTERISTICS Table 3-3 General Specifications of the Motor Item Specification Type Drive method Bipolar chopper Excitation 2-2 phase 14 Ω ±10% Winding resistance per phase Rated voltage 4.5 - 8.5 V Rated current 0.30 A/phase Maximum current consumption 0.60 A Drive frequency 200 - 1440 pps (according to drive voltage)
  • Page 18 3.4.1 Motor Drive Circuit (1) Sample Drive Circuit Sample drive circuit for the motor is shown in Figure 3-3. 10V, 10V, 10V, 10V, Figure 3-3 Sample Drive Circuit...
  • Page 19 (2) Excitation Sequence As shown in Table 3-4, the printer feeds paper in the normal direction when the motor is excited in the order of step 1, step 2, step 3, step 4, step 1, step 2, ..Do not feed paper in the reverse direction.
  • Page 20 3.4.2 Motor Timing Refer to the timing chart in Figure 3-5 when designing the control circuit and/or software for starting and stopping the motor. Also take note of the following precautions: Precautions for Designing the Motor Control Circuit and Software (1) Stop step ! To stop the motor, excite for 5 ms with a phase that is the same as the final one in the printing step.
  • Page 21 (4) Others ! To print characters and bit images, always follow the start step and stop step. ! When the motor step is stopped in the dot lines where head activation was performed, the thermal head may stick to the surface of the paper and cause paper feed problems. Therefore, stop the motor drive in the dot lines where head activation is not performed.

  • Page 22: Acceleration Control

    3.4.3 Precautions for Driving the Motor (1) Motor Current Control When the motor speed decreases during printing because of the division drive method, the contents of print data, or input data transfer speed, noise and overheating of the motor may occur due to over- torque of the motor.
  • Page 23 Table 3-5 Acceleration Steps Number of Speed Step Time (µ µ µ µ s) Steps (pps)  start 5000 4875 3013 2327 1953 1712 1541 1412 1310 1227 1158 1099 1048 1004 1037 1076 1114 1150 1186 1220 1254 1287 1318 1350 1380...

  • Page 24: Thermal Head

    THERMAL HEAD 3.5.1 Structure of the Thermal Head As shown in Figure 3-6, the thermal head of the printer consists of 384 heat elements, and head drivers to drive the heat elements. Serial printing data input from the DAT terminal is transferred to the shift register synchronously with the CLK signal, then stored in the latch register with the timing of the LATCH signal.
  • Page 25 Block6 Block5 Blcok2 Block1 Heat Element Output Driver Latch Register Shift Register LATCH DST6 DST5 DST2 DST1 Thermistor Figure 3-6 Thermal Head Block Diagram 3-13...
  • Page 26 Table 3-6 Blocks and Activated Heat Elements Block Number Heat Element Number Dots/DST 1 - 64 65 - 128 129 - 192 193 - 256 257 - 320 321 - 384 3.5.2 Printed Position of the Data Data dots from 1 to 384 which are transferred through DAT are printed as shown in Figure 3-7. PAPER FEED DIRECTION PAPER PRINT SURFACE...
  • Page 27 3.5.3 Head Voltage The printer has a built-in head driver IC. Table 3-7 shows the head voltage. Table 3-7 Head Voltage Item Voltage Range Head drive voltage 4.5 to 8.5 V Head logic voltage 2.7 to 5.25 V 3.5.4 Peak Current Since the peak current (maximum current) may reach the values calculated using equation (3) shown below when the thermal head is driven, make sure that the allowable current for the cable material and the voltage drop on the cables are well within the specified range.
  • Page 28 3.5.5 Thermal Head Electrical Characteristics Table 3-8 LTPA245 Thermal Head Electrical Characteristics Environmental temperature Ta=25°C Rated Values Item Simbol Conditions Unit Ω Head average resistance Head drive voltage Head drive current max. simultaneously activated dot 64 Logic block voltage 5.25 Logic block current fclk=8 MHz, DAT=1/2fclk "High"...

  • Page 29: Timing Chart

    3.5.6 Timing Chart 1/f clk 1/‚ † clk ‚ ” 1 ‚ ” 6 ‚ b ‚ k ‚ j ‚ ” 2 ‚ ” 3 ‚ c ‚ ` ‚ s ‚ ” 4 ‚ ” 5 ‚ ” 7 LATCH ‚...
  • Page 30 CONTROLLING THE HEAD ACTIVATION (DST) PULSE WIDTH 3.6.1 Calculation of Head Activation Pulse Width Head activation pulse width is calculated using the following equation (4). To execute high quality printing using the printer, the value that is calculated using the following equation (4) must be adjusted according to the environment the printer is used in.
  • Page 31 3.6.3 Calculation of Head Activation Voltage Calculate the applied voltage using equation (6). Equation (6): V=Vp × 1.2 - 1.3 Vp: Head activation voltage (V) 3.6.4 Calculation of Head Resistance A drop in voltage occurs depending on the wiring resistance. Calculate the head resistance using equation (7).
  • Page 32 3.6.5 Head Activation Pulse Term Coefficient Make adjustments using the head activation pulse term coefficient (equal motor drive frequency) as the printing density changes by the printing speed. According to equations (8), calculate compensation coefficient C of the activation pulse. Equation (8): C = 1 –...
  • Page 33 3.6.7 Heat Storage Coefficient In high speed printing, a difference in temperature arises between the rise in temperature of the thermal head due to head activation and the temperature detected by the thermistor. Therefore, the activation pulse must be corrected by simulating a rise in the temperature of the thermal head. No correction is needed when the print ratio is low.
  • Page 34 3.6.8 Calculation Sample for the Head Activation Pulse Width Table 3-9 lists the calculation sample of the head activation pulse width that was calculated substituting the values obtained using equations (5) to (9) and the heat storage coefficient when D=1 for equation (4).

  • Page 35: Thermistor Resistance

    3.6.9 Thermistor Resistance The resistance of the thermistor at the operating temperature T (°C) is determined using the following equation (11). Equation (11): × EXP B ×  -  273 + T Resistance at operating temperature Tx (°C) 30 kΩ ± 5% (25°C) 3950 k ±...
  • Page 36 Table 3-10 Temperature and Thermistor Resistance Temperature Thermistor Temperature Thermistor (° ° ° ° C) Resistance (kΩ Ω Ω Ω ) (° ° ° ° C) Resistance (kΩ Ω Ω Ω ) 132.3 10.8 101.0 77.9 60.6 47.5 37.6 30.0 24.1 19.5 15.9...
  • Page 37 3.6.10 Detecting Abnormal Temperatures of the Thermal Head To protect the thermal head and to ensure personal safety, abnormal thermal head temperatures must be detected by both hardware and software as follows: ! Detecting abnormal temperatures by software Design software that will deactivate the heat elements if the thermal head thermistor (TH) detects a temperature 80°C or higher (thermistor resistance RTH ≤...
  • Page 38 PAPER DETECTOR The printer has a built-in paper detector (reflection type photo interrupter) to detect whether paper is present or not. An external circuit should be designed so that it detects output from the paper detector and does not activate the thermal head and motor when there is no paper. Doing not so may cause damage to the thermal head or platen roller or shorten the longevity of the head significantly.
  • Page 39 Table 3-12 Paper Detectors Input/Output Conditions Item Symbol Conditions Standard Max. Forward voltage =10mA 1.2V 1.6V − (input) Reverse current 10µA Photo- − transistor Dark current If=0mA, V =10V 200nA (output) − Transfer Photo electric =10mA, V 350µA characteristics current −...
  • Page 40 CHAPTER CONNECTING EXTERNAL CIRCUITS The printer has an FPC type connector with 1-mm pitch pins. Use the recommended connectors listed in Table 4-1 to connect the printer firmly to the external circuits. Table 4-1 Recommended Connectors External Circuit Number of Recommended Connectors Functions Pins...
  • Page 41 Table 4-2 Thermal Head Control Terminal Assignments Terminal Signal Input/ Function Number Name Output Output Paper detector receiving photo collector output Input Paper detector luminous portion Paper detector GND Thermal head drive voltage Thermal head drive voltage Input Print data input (serial input) DST6 Input Thermal head print activation instruction signal...
  • Page 42 CAUTION IN CONNECTION Pay attention to the following during installation of the printer. " Always remove or install the thermal head controls vertically while holding the reinforcement portion of the FPC. " Do not bend the FPC. If the FPC must be bent unavoidably, try to do so without removing the reinforcement sheet from the reinforcement portion of the FPC.
  • Page 43 CHAPTER DRIVE METHOD THERMAL HEAD DRIVE TIMING ! Input of print data Input of DAT and CLK transfer the print data to the shift register in the serial input. “High” means printing and “Low” means no-printing in DAT. DAT data is read in at the rising edge of the CLK inputs.
  • Page 44 MOTOR DRIVE TIMING To print, the phase of motors need to be synchronized with that of the thermal head. As example, the print method which divides one dot line to two groups; the block 1,3, and 5 and the block 2,4, and 6, and prints each group data for each step of the motor is described below. The basic pulse width of the motor drive pulse, Tm, is a value (unit: msec) of the reciprocal number of the driving frequency calculated using equation (1) and (2) of "3.3 PAPER FEED CHARACTERISTICS".
  • Page 45 ! 2nd dot line, 1st step Drive the motor by one step (3rd step). As to how much step time is output, compare Tm with the time that was taken in the previous step. (1) in case Tm < the time that was taken in the previous step the next closest acceleration step time to the previous step time or Tm, which is longer, is output.
  • Page 46 Figure 5-2 shows an example of the motor drive timing chart. 1st STEP OF 2nd STEP OF 2nd STEP OF STOP START 1st STEP OF THE 1st DOT LINE THE 2nd DOT LINE THE 1st DOT LINE THE 2nd DOT LINE LATCH Figure 5-2 Example of Motor Drive Timing Chart...

  • Page 47: Securing The Printer

    CHAPTER HOUSING DESIGN GUIDE SECURING THE PRINTER The main body of the printer and platen block must be secured to the outer case separately with screws. 6.1.1 Printer Mounting Method Secure the printer with a hole E and 2 pawls (C, D), as shown below. Holes A and B are used for positioning the body of the printer.
  • Page 48 6.1.2 Connecting FG Cable Connect the FG cable to the FG plate of the printer with the FG cable lock screw. Prepare the FG cable and FG cable lock screw of the types shown in Figure 6-2. For the application terminals of the FG cable, the type shown in Figure 6-3 is recommended. FG plate Application terminal (round)
  • Page 49 Recommended Screw The recommended mounting screw is as follows: Screw: Cross-recessed pan head tapping screw to secure resinated material (nickel plating) nominal size: 2 mm, length from below the head: 5 mm Screw Fastening Torque Reference value: 2.4 to 3.0 kgf-cm Fasten the screw on a flat surface, placing the FG plate surface of the printer upward from above.
  • Page 50 Referring to Figure 6-5, design the shape of the platen support so that the platen support does not come in contact with the head block. For the operational sizes of the lock arm lever and head block, see Figure 7-4. Unit: mm Figure 6-5 How to Secure the Platen Block (LTPA245A: (2))
  • Page 51 When using LTPA245B, LTPA245C or LTPA245D: Prepare the paper holder cover and provide it with the two screw holes (H, I) and the two boss shapes (F, G) for positioning as shown in Figure 6-6, to secure the platen block. When designing the paper holder cover, use the dimensions shown below.
  • Page 52 Recommended Screws The recommended mounting screws are as follows: 1) Screw: JIS B1111 cross-recessed pan head machine screw: M2.5 to 2.6 2) Screw: Cross-recessed pan head tapping screw to secure resinated material: nominal 2.5 to 2.6 mm 6.1.4 Precautions for Securing the Printer Pay attention to the following when designing the case and securing the printer.
  • Page 53 LAYOUT OF PRINTER AND PAPER The printer can be laid out as shown in Figure 6-7 according to the loading direction of the paper. l Design the paper outlet with an angle of 60 to 90°. l Design the paper inlet with an angle of 90 to 150°. Design the printer so that the paper feed force is 0.49N (50 gf) or less.

  • Page 54: Setting The Paper

    SETTING THE PAPER Follow these precautions when setting the paper. l Be sure to use the recommended paper described in this technical reference. l Place the paper roll into the holder facing the thermal surface outward. Also, do not use paper with edges that are pasted or have turnups at the start of the roll.
  • Page 55 Figure 6-9 shows the shape of the blade of the paper cutter that should be used. The Blade of the Cutter The Blade of the Cutter Not Good Good Figure 6-9 The Blade of the Paper Cutter In the left cutter of Figure 6-9, the cut paper may be caught by the blade of the cutter and rolled inside. Therefore, use a cutter with the shape of a blade that will not catch the cut paper as in Figure 6-9 to the right.

  • Page 56: Appearance And Dimensions

    CHAPTER APPEARANCE AND DIMENSIONS Figures 7-1, 7-2, 7-3, 7-4, 7-5, 7-6, 7-7, 7-8, 7-9, 7-10, 7-11, 7-12, and 7-13 show the appearance and external dimensions of the LTPA245.
  • Page 57 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-1 LTPA245A Appearance and Dimensions...
  • Page 58 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-2 LTPA245A Printer Main Body Appearance and Dimensions...
  • Page 59 Unit: mm Figure 7-3 LTPA245A Platen Block Appearance and Dimensions...
  • Page 60 Unit: mm Figure 7-4 Lever of LTPA245A and LTPA245D Lock Arm and Head Block Operations...
  • Page 61 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-5 LTPA245B Appearance and Dimensions...
  • Page 62 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-6 LTPA245B Printer Main Body Appearance and Dimensions...
  • Page 63 Unit: mm Figure 7-7 LTPA245B, LTPA245C, and LTPA245D Platen Block Appearance and Dimensions...
  • Page 64 Lever (lock arm) Unit: mm Figure 7-8 Lever of LTPA245B Lock Arm and Head Block Operations...
  • Page 65 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-9 LTPA245C Appearance and Dimensions 7-10...
  • Page 66 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-10 LTPA245C Printer Main Body Appearance and Dimensions 7-11...
  • Page 67 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-11 Lever of LTPA245C Lock Arm and Head Block Operations 7-12...
  • Page 68 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-12 LTPA245D Appearance and Dimensions 7-13...
  • Page 69 General Dimensional Tolerance Less than 30 mm: ±0.2 30 mm or more: ±0.3 Unit: mm Figure 7-13 LTPA245D Printer Main Body Appearance and Dimensions 7-14...
  • Page 70 CHAPTER LOADING/UNLOADING PAPER AND HEAD CLEANING LOADING/UNLOADING PAPER PRECAUTIONS 8.1.1 LTPA245A and LTPA245D Procedures for Loading/Unloading Paper 1) Loading paper ! Turn the lever (projection) of the lock arm in the direction of the arrow shown in Figure 8-1. Figure 8-1 Loading Paper (1) ! After confirming that the platen block has separated from the printer mechanism, lift the platen block up (Open state).
  • Page 71 ! Insert the paper vertically into the printer. (See Figure 8-2). Pull the paper outside the paper outlet and place the platen block into the printer mechanism firmly. Make sure that the platen block locks with a click (Close state). Figure 8-2 Loading Paper (2) ! Opening the platen block exposes the reduction gear.
  • Page 72 8.1.2 LTPA245B and LTPA245C Procedures for Loading/Unloading Paper 1) Loading paper ! Turn the lever (projection) of the lock arm in the direction of the arrow shown in Figure 8-3. (for LTPA245B) ! Turn the lever (projection) of the lock arm in the direction of the arrow shown in Figure 8-3 to open the platen block.
  • Page 73 Figure 8-4 Loading Paper (2) ! A reduction gear exposes in the open position of the platen block. Operate the reduction gear carefully so as not to be damaged. The reduction gear damage affects paper feed difficulties. Verify no foreign substances on the reduction gear. ! If foreign substances are attached to or accumulated on the paper sensor (photo-interrupter), a detection error may occur.

  • Page 74: Head Cleaning Procedure And Precautions

    HEAD CLEANING PROCEDURE AND PRECAUTIONS 8.2.1 Precautions Do not clean the thermal head immediately after printing because thermal head and its periphery are hot during and after printing. Do not use sandpaper, cutter knives etc. when cleaning. They will damage the heat elements.

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